core: Standardize RemoveSnapshot.canDoAction

Set the action and the type parameters in the
setActionMessageParameters(), which is supported in CommandBase's
framework.

The old workaround was removed, resulting in a cleaner canDoAction()
method.

Change-Id: I93f391984827fa5deb816d8856a982bf03b77df1
Signed-off-by: Allon Mureinik <amureini@redhat.com>